We will be applying an Apache update to all servers on our Shared & Reseller platform later this evening. This will take the Apache install from 2.2.21 to 2.2.22 and resolve a number of vulnerabilities patched in the 2.2.22 release.
The vulnerabilities present in 2.2.21 allow for the possibility of privilege escalation, crashes and DoS attacks. As this is a security issue and the servers are a shared platform we will be performing emergency maintenance between midnight and 3am (GMT).
The work will involve a restart of the Apache service - this may result in around 10seconds of slowness however no noticeable impact should be observed. The primary and secondary PHP stacks will remain un-touched and no configuration changes will be made.
In the worst cast scenario (such as a failed compile) the installer will restore a backup of the current working installation.
You can view the Apache change log on the apache.org side (http://www.apache.org/dist/httpd/CHANGES_2.2.22).